<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.0/jquery.js"></script>
</head>

<body>
    <button>开灯</button>
    <img src="img/1.png" alt="">
</body>
<script>
    $(function () {
        $('button').click(function () {
            var but = $('button').html()
            $('img').attr('src', 'img/2.png')
            $(this).html('关灯')
            if (but == '关灯') {
                $('img').attr('src', 'img/1.png')
                $(this).html('开灯')
            }
        })

    })
</script>

</html>